There are two main foci in this research. The first has to do with police officers' management of psychiatric referrals, using their powers under Section 136 of the Mental Health Act, the second with interprofessional relations between the police and psychiatrists. A Section 136 case is defined so as to include all referrals where a mental health disposal is initiated by the police as opposed to a court or other mental health professional. The research is an attempt to describe police officers involvement with psychiatric referrals and the nature of and reasons behind the decisions they make, and to understand the nature of professional relationships that exist between police officers and psychiatrists in applying this part of the Mental Health Act. The concepts used, and theoretical underpinnings of the research are in the main derived from the sociology of 'mental illness'. Use, has been made of the theory of professional dominance to analyse police action and interaction with psychiatrists. Both quantitative and qualitative methods of data collection and analysis have been used. Primacy has not been given to one or other approach, rather an attempt has been made to integrate both, so as to present as full a picture as possible of the issues under investigation. Data was primarily collected by means of interviews with police officers from 11 different police stations in the North East Metropolitan Police area. This was supplemented by the use of participant observation at one police station, interviews with psychiatrists at two hospitals and analysis of police documents and administrative records. The study has been divided into three sections: preparing for and carrying out the research (Chapters 1-4); the analysis and presentation of findings (Chapters 5-8); discussion and implications of the results and re-examining the theory (Chapter 9-10). It was rare for officers to initiate referrals themselves, it was mainly as a response to others that they became involved. Officers were generally unaware that they were responding to a mental health emergency prior to arriving at an incident, and decisions to apprehend were made for policing rather than psychiatric reasons. Officers did not always use Section 136 as an authority for arrest where a psychiatric disposal was subsequently sought. A combination of physical restraint and verbal strategies were used to manage referrals. Officers tended not to treat these differently to other suspects, whilst on the streets, but treated them less punitively than other detainees once at the station. It was found that there was a tendency to exclude other forms of deviancy in identifying mental disorder. Most referrals could have been charged with a criminal offence and officers' reasons for not preferring charges were examined, of which external considerations, (such as the policy of the courts) were found to be important. Police and psychiatrists generally shared the same perceptions about their client group in terms of the latter's appropriateness to be dealt with by the psychiatric services. With the exception of police ability to diagnose mental disorder, there was agreement about the nature of officer's role in relation to Section 136. Interprofessional contact and perceptions of one another were characterised by distance and indifference. At the hospital, psychiatrists assumed a superordinate role over the police officers. However, police officers exercised considerable autonomy over decision making at the police station which acted to threaten the psychiatrists gatekeeping powers.